1. Field of the Invention
The invention relates to an abrasive grinding wheel in the form of a thin grinding wheel, provided with a plurality of stacked layers of constituents bonded by pressure.
2. Description of the Related Art
Such grinding wheels are made by stacking, generally around a central metal bushing, a protective paper disk, a reinforcing sheet generally of cloth or similar meshed, perforated or honeycombed material, a layer of abrasive grains, another reinforcing sheet, also generally of cloth or similar material, and if necessary another protective paper disk; thereupon the stack is generally heated; then it is pressed and, as a result, the layer of abrasive grains and the meshed, perforated or honeycombed reinforcement layers are generally made to interlock at least partly as a result of penetration of the abrasive grains into the meshes, perforations or honeycombs.
At present, these grinding wheels have an offset hub, meaning that the part of the grinding wheel that is in the immediate vicinity of the central bushing does not extend in the same plane as the part surrounding it, and the grinding wheel is mounted on the grinding machine in such a way that this part most distant from the bushing projects the most beyond the machine; the grinding wheel is therefore generally used for surface treatment only on the surface of this part situated on the side opposite the machine; for cutting-off operations, it is naturally the circumference of the same part that is subjected to the greatest load. It is therefore essential that this part contain very high-performance grains, and it is uselessly costly for the part close to the bushing to contain the same abrasive grains, as is the case in conventional grinding wheels.
Furthermore, during rotation of the grinding wheel, the circumferential velocity of the abrasive grains close to the circumference is very much higher than that of the grains closer to the bushing, and so the optimal abrasives for the two regions are not necessarily the same.